/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.thinkinbunny.codec.digest;

import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.thinkinbunny.codec.binary.Hex;
import org.thinkinbunny.codec.binary.StringUtils;

/**
 * Operations to simplify common {@link java.security.MessageDigest} tasks. This
 * class is thread safe.
 * 
 * @version $Id: DigestUtils.java 1380826 2012-09-04 19:35:06Z ggregory $
 */
public class DigestUtils {

	private static final int STREAM_BUFFER_LENGTH = 1024;

	/**
	 * Read through an InputStream and returns the digest for the data
	 * 
	 * @param digest
	 *            The MessageDigest to use (e.g. MD5)
	 * @param data
	 *            Data to digest
	 * @return MD5 digest
	 * @throws IOException
	 *             On error reading from the stream
	 */
	private static byte[] digest(MessageDigest digest, InputStream data)
			throws IOException {
		byte[] buffer = new byte[STREAM_BUFFER_LENGTH];
		int read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);

		while (read > -1) {
			digest.update(buffer, 0, read);
			read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);
		}

		return digest.digest();
	}

	/**
	 * Calls {@link StringUtils#getBytesUtf8(String)}
	 * 
	 * @param data
	 *            the String to encode
	 * @return encoded bytes
	 */
	private static byte[] getBytesUtf8(String data) {
		return StringUtils.getBytesUtf8(data);
	}

	/**
	 * Returns a <code>MessageDigest</code> for the given <code>algorithm</code>
	 * .
	 * 
	 * @param algorithm
	 *            the name of the algorithm requested. See <a href=
	 *            "http://java.sun.com/j2se/1.3/docs/guide/security/CryptoSpec.html#AppA"
	 *            >Appendix A in the Java Cryptography Architecture API
	 *            Specification & Reference</a> for information about standard
	 *            algorithm names.
	 * @return An MD5 digest instance.
	 * @see MessageDigest#getInstance(String)
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught.
	 */
	public static MessageDigest getDigest(String algorithm) {
		try {
			return MessageDigest.getInstance(algorithm);
		} catch (NoSuchAlgorithmException e) {
			throw new IllegalArgumentException(e);
		}
	}

	/**
	 * Returns an MD2 MessageDigest.
	 * 
	 * @return An MD2 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because MD2 is a built-in algorithm
	 * @see MessageDigestAlgorithms#MD2
	 * @since 1.7
	 */
	public static MessageDigest getMd2Digest() {
		return getDigest(MessageDigestAlgorithms.MD2);
	}

	/**
	 * Returns an MD5 MessageDigest.
	 * 
	 * @return An MD5 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because MD5 is a built-in algorithm
	 * @see MessageDigestAlgorithms#MD5
	 */
	public static MessageDigest getMd5Digest() {
		return getDigest(MessageDigestAlgorithms.MD5);
	}

	/**
	 * Returns an SHA-1 digest.
	 * 
	 * @return An SHA-1 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because SHA-1 is a built-in algorithm
	 * @see MessageDigestAlgorithms#SHA_1
	 * @since 1.7
	 */
	public static MessageDigest getSha1Digest() {
		return getDigest(MessageDigestAlgorithms.SHA_1);
	}

	/**
	 * Returns an SHA-256 digest.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @return An SHA-256 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because SHA-256 is a built-in algorithm
	 * @see MessageDigestAlgorithms#SHA_256
	 */
	public static MessageDigest getSha256Digest() {
		return getDigest(MessageDigestAlgorithms.SHA_256);
	}

	/**
	 * Returns an SHA-384 digest.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @return An SHA-384 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because SHA-384 is a built-in algorithm
	 * @see MessageDigestAlgorithms#SHA_384
	 */
	public static MessageDigest getSha384Digest() {
		return getDigest(MessageDigestAlgorithms.SHA_384);
	}

	/**
	 * Returns an SHA-512 digest.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @return An SHA-512 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught, which
	 *             should never happen because SHA-512 is a built-in algorithm
	 * @see MessageDigestAlgorithms#SHA_512
	 */
	public static MessageDigest getSha512Digest() {
		return getDigest(MessageDigestAlgorithms.SHA_512);
	}

	/**
	 * Returns an SHA-1 digest.
	 * 
	 * @return An SHA-1 digest instance.
	 * @throws IllegalArgumentException
	 *             when a {@link NoSuchAlgorithmException} is caught
	 * @deprecated Use {@link #getSha1Digest()}
	 */
	@Deprecated
	public static MessageDigest getShaDigest() {
		return getSha1Digest();
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest
	 * @since 1.7
	 */
	public static byte[] md2(byte[] data) {
		return getMd2Digest().digest(data);
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.7
	 */
	public static byte[] md2(InputStream data) throws IOException {
		return digest(getMd2Digest(), data);
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest
	 * @since 1.7
	 */
	public static byte[] md2(String data) {
		return md2(getBytesUtf8(data));
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest as a hex string
	 * @since 1.7
	 */
	public static String md2Hex(byte[] data) {
		return Hex.encodeHexString(md2(data));
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.7
	 */
	public static String md2Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(md2(data));
	}

	/**
	 * Calculates the MD2 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD2 digest as a hex string
	 * @since 1.7
	 */
	public static String md2Hex(String data) {
		return Hex.encodeHexString(md2(data));
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest
	 */
	public static byte[] md5(byte[] data) {
		return getMd5Digest().digest(data);
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static byte[] md5(InputStream data) throws IOException {
		return digest(getMd5Digest(), data);
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 16 element
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest
	 */
	public static byte[] md5(String data) {
		return md5(getBytesUtf8(data));
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest as a hex string
	 */
	public static String md5Hex(byte[] data) {
		return Hex.encodeHexString(md5(data));
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static String md5Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(md5(data));
	}

	/**
	 * Calculates the MD5 digest and returns the value as a 32 character hex
	 * string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return MD5 digest as a hex string
	 */
	public static String md5Hex(String data) {
		return Hex.encodeHexString(md5(data));
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 * @deprecated Use {@link #sha1(byte[])}
	 */
	@Deprecated
	public static byte[] sha(byte[] data) {
		return sha1(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 * @deprecated Use {@link #sha1(InputStream)}
	 */
	@Deprecated
	public static byte[] sha(InputStream data) throws IOException {
		return sha1(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 * @deprecated Use {@link #sha1(String)}
	 */
	@Deprecated
	public static byte[] sha(String data) {
		return sha1(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 * @since 1.7
	 */
	public static byte[] sha1(byte[] data) {
		return getSha1Digest().digest(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.7
	 */
	public static byte[] sha1(InputStream data) throws IOException {
		return digest(getSha1Digest(), data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a
	 * <code>byte[]</code>.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest
	 */
	public static byte[] sha1(String data) {
		return sha1(getBytesUtf8(data));
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @since 1.7
	 */
	public static String sha1Hex(byte[] data) {
		return Hex.encodeHexString(sha1(data));
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.7
	 */
	public static String sha1Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(sha1(data));
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @since 1.7
	 */
	public static String sha1Hex(String data) {
		return Hex.encodeHexString(sha1(data));
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest
	 * @since 1.4
	 */
	public static byte[] sha256(byte[] data) {
		return getSha256Digest().digest(data);
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static byte[] sha256(InputStream data) throws IOException {
		return digest(getSha256Digest(), data);
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest
	 * @since 1.4
	 */
	public static byte[] sha256(String data) {
		return sha256(getBytesUtf8(data));
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest as a hex string
	 * @since 1.4
	 */
	public static String sha256Hex(byte[] data) {
		return Hex.encodeHexString(sha256(data));
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static String sha256Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(sha256(data));
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-256 digest as a hex string
	 * @since 1.4
	 */
	public static String sha256Hex(String data) {
		return Hex.encodeHexString(sha256(data));
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest
	 * @since 1.4
	 */
	public static byte[] sha384(byte[] data) {
		return getSha384Digest().digest(data);
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static byte[] sha384(InputStream data) throws IOException {
		return digest(getSha384Digest(), data);
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest
	 * @since 1.4
	 */
	public static byte[] sha384(String data) {
		return sha384(getBytesUtf8(data));
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest as a hex string
	 * @since 1.4
	 */
	public static String sha384Hex(byte[] data) {
		return Hex.encodeHexString(sha384(data));
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static String sha384Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(sha384(data));
	}

	/**
	 * Calculates the SHA-384 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-384 digest as a hex string
	 * @since 1.4
	 */
	public static String sha384Hex(String data) {
		return Hex.encodeHexString(sha384(data));
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest
	 * @since 1.4
	 */
	public static byte[] sha512(byte[] data) {
		return getSha512Digest().digest(data);
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static byte[] sha512(InputStream data) throws IOException {
		return digest(getSha512Digest(), data);
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a
	 * <code>byte[]</code>.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest
	 * @since 1.4
	 */
	public static byte[] sha512(String data) {
		return sha512(getBytesUtf8(data));
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest as a hex string
	 * @since 1.4
	 */
	public static String sha512Hex(byte[] data) {
		return Hex.encodeHexString(sha512(data));
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 */
	public static String sha512Hex(InputStream data) throws IOException {
		return Hex.encodeHexString(sha512(data));
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a hex string.
	 * <p>
	 * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
	 * </p>
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-512 digest as a hex string
	 * @since 1.4
	 */
	public static String sha512Hex(String data) {
		return Hex.encodeHexString(sha512(data));
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @deprecated Use {@link #sha1Hex(byte[])}
	 */
	@Deprecated
	public static String shaHex(byte[] data) {
		return sha1Hex(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @throws IOException
	 *             On error reading from the stream
	 * @since 1.4
	 * @deprecated Use {@link #sha1Hex(InputStream)}
	 */
	@Deprecated
	public static String shaHex(InputStream data) throws IOException {
		return sha1Hex(data);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param data
	 *            Data to digest
	 * @return SHA-1 digest as a hex string
	 * @deprecated Use {@link #sha1Hex(String)}
	 */
	@Deprecated
	public static String shaHex(String data) {
		return sha1Hex(data);
	}

	/**
	 * Updates the given {@link MessageDigest}.
	 * 
	 * @param messageDigest
	 *            the {@link MessageDigest} to update
	 * @param valueToDigest
	 *            the value to update the {@link MessageDigest} with
	 * @return the updated {@link MessageDigest}
	 * @since 1.7
	 */
	public static MessageDigest updateDigest(final MessageDigest messageDigest,
			byte[] valueToDigest) {
		messageDigest.update(valueToDigest);
		return messageDigest;
	}

	/**
	 * Updates the given {@link MessageDigest}.
	 * 
	 * @param messageDigest
	 *            the {@link MessageDigest} to update
	 * @param valueToDigest
	 *            the value to update the {@link MessageDigest} with
	 * @return the updated {@link MessageDigest}
	 * @since 1.7
	 */
	public static MessageDigest updateDigest(final MessageDigest messageDigest,
			final String valueToDigest) {
		messageDigest.update(getBytesUtf8(valueToDigest));
		return messageDigest;
	}
}
